INTRODUCTION TO HARD DISK DRIVESA Brief History of the Hard plough DriveThe hard disk control has short and fascinating history. In 24 years it evolved from a monstrosity with fifty two-foot diameter disks holding five MBytes (5,000,000 bytes) of data to today's drives measuring 3 /12 inches wide and an inch high (and smaller) holding 400 GBytes (400,000,000,000 bytes/characters). Here then is the short history of this marvelous device. Before the plough drive there were drums... In 1950 Engineering Research Associates of Minneapolis built the first commercial magnetic drum storage unit for the U. S. Navy the ERA 110. It could hold on one million bits of data and retrieve a evince in 5 thousandths of a back up. In 1956 IBM invented the first computer disk storage system the 305 RAMAC (Random find Method of Accounting and Control). This system could hold on five MBytes. It had fifty. 24-inch diameter disks!By 1961 IBM had invented the first disk control with air bearing heads and in 1963 they introduced the removable disk case control. In 1970 the eight advance floppy disk control was introduced by IBM. My first floppy drives were made by Shugart who was one of the "dirty dozen" who left IBM to start their own companies. In 1981 two Shugart 8 inch floppy drives with enclosure and power supply cost me about $350.00. They were for my back up computer. My first computer had no drives at all. In 1973 IBM shipped the copy 3340 Winchester sealed hard disk drive the predecessor of all current hard disk drives. The 3340 had two spindles each with a capacity of 30 MBytes and the term "30/30 Winchester" was thus coined. What is an IDE Hard Disk Drive?Integrated control Electronics (IDE) hard disks undergo been around for quite a few years. Prior to these drives hard disks were interfaced to a PC motherboard via an expansion board known as a hard disk controller. The drive did most of the mechanical stuff and performed basic electronic/servo functions; the controller told it in dilate what to do. The development of the IDE hard moved most of the electronics and firmware (low-level software on a divide) from the controller to a printed go board on the drive itself. In the affect a buffer/cache' memory was added to the electronics to speed-up the affect of reading and writing hard plough drive data. The drive got "smarter." Overall costs went drink and performance went up. A much simpler board commonly known as an IDE Controller interfaced the IDE hard disk to the motherboard bus. The call IDE Controller is a misnomer. It is actually nothing more than a bus interface and an interface and connector for the IDE cable going to the control. The actual controller is on the drive. In most cases when a computer says it has a problem with the hard disk controller it has a problem with the electronics on the drive. Subsequently the IDE Controller expansion come in electronics and the connector for the control telecommunicate were incorporated into most motherboards. Most of these motherboards have two IDE interfaces--a Primary and a Secondary--each of which can support two IDE devices. The term Integrated Drive Electronics (IDE) is owned by Western Digital. Other companies such as Maxtor. Quantum and Seagate use the term ATA (AT Attachment). IDE and ATA are the same thing. Several standards have subsequently been developed to improve upon the IDE drive and incorporate other devices such as CD-ROMs which can operate off the IDE interfaces: Enhanced IDE (EIDE). ATAPI (ATA Packet Interface). Ultra-ATA etc. Today most hard disk drives manufactured for PCs are ATA/66 drives (ATA/100 is proably around the corner). These drives use Bus Mastering and enjoin Memory Access to transfer data back and forth between the disk control and the computer memory with burst speeds up to a theoretical 66 Mega Bytes per back up (MBs) without going through the processor. Older ATA/33 (Ultra DMA) drives do the same thing at 33 MBs. Many existing motherboards still have ATA/33 or even older IDE interfaces. Most ATA/66 drives will work on the older IDE interfaces but of course not as abstain. The other study category of disk drives use variations of the Small Computer System Interface (SCSI) and will not be covered in the first publication of this guideHow a Hard plough Drive WorksHARD plough ASSEMBLYA hard plough drive consists of a motor spindle platters construe/write heads actuator close in air filter and electronics. The frame mounts the mechanical parts of the control and is sealed with a adjoin. The sealed part of the drive is known as the Hard Disk Assembly or HDA. The control electronics usually consists of one or more printed circuit boards mounted on the furnish of the HDA. A head and platter can be visualized as being similar to a preserve and playback continue on an old phonograph object the data structure of a hard plough is arranged into concentric circles instead of in a spiral as it on a phonograph record (and CD-ROM). A hard disk has one or more platters and each platter usually has a continue on each of its sides. The platters in modern drives are made from furnish or ceramic to forbid the unfavorable thermal characteristics of the aluminum platters found in older drives. A forge of magnetic material is deposited/sputtered on the ascend of the platters and those in most of the drives I've dissected have shiny chrome-like surfaces. The platters are mounted on the spindle which is turned by the drive motor. Most current IDE hard disk drives go around at 5,400. 7,200 or 10,000 RPM and 15,000 RPM drives are emerging. In 1980. Seagate Technology introduced the first hard plough control for microcomputers the ST506. It was a full height (twice as high as most current 5 1/4" drives) 5 1/4" drive with a stepper motor and held 5 Mbytes. My first hard plough control was an ST506. I cannot remember exactly how much it cost but it plus its enclosure etc was come up over a thousand dollars. It took me three years to fill the drive. Also in 1980 Phillips introduced the first optical laser drive. In the early 80's the first 5 1/4" hard disks with voice turn actuators (more on this later) started shipping in volume but stepper go drives continued in production into the early 1990's. In1981. Sony shipped the first 3 1/2" floppy drives. In 1983 Rodime made the first 3.5 advance rigid plough drive. The first CD-ROM drives were shipped in 1984 and "Grolier's Electronic Encyclopedia," followed in 1985. The 3 1/2" IDE drive started its existence as a drive on a plug-in expansion board or "hard separate." The hard card included the drive on the controller which in turn evolved into Integrated Device Electronics (IDE) hard plough drive where the controller became incorporated into the printed circuit on the furnish of the hard plough drive. Quantum made the first hard card in 1985. In 1986 the first 3 /12" hard disks with express coil actuators were introduced by Conner in volume but half (1.6") and beat height 5 1/4" drives persisted for several years. In 1988 Conner introduced the first one inch high 3 1/2" hard plough drives. In the same year PrairieTek shipped the first 2 1/2" hard disksIn 1997 Seagate introduced the first 7,200 RPM. Ultra ATA hard disk control for desktop computers and in February of this year they introduced the first 15,000 RPM hard disk control the Cheetah X15. Milestones for IDE DMA. ATA/33 and ATA/66 drives go:1994 DMA. Mode 2 at 16.6 MB/s1997 Ultra ATA/33 at 33.3 MB/s1999 Ultra ATA/66 at 66.6 MB/s6/20/00 IBM triples the capacity of the world's smallest hard plough drive. This control holds one gigabyte.
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